Cutter chain



' Novas', 1941. c. F. QSGOOVD A 2,263,590

CUTTER CHAIN l Filed Jan. 22, 195e s "sheets-sheet 1 IMI iz veil Z071- Uzar/efl? sjoof Nov. 25, 1941. c. F. osGooD 2,263,590

. k GUTTER CHAIN Filed Jan. 22, 1936 3 Sheets-Sheet 2 @fri mlm W 3W A @Mk2/@Wm day;

Patented Nov.` 25, 1941 GUTTER CHAIN -Charles F. Osgood, ClaremonhN. H., assgnorto Sullivan Machinery Company, a corporation of Massachusetts Application January '22, 1936, Serial No. 60,17 9

13 Claims. ,(Ql. 26E-33) This invention relates to cutter chains, and more particularly to improvements in cutter chains especially designed for use with coal cut-- ting machinery.

An object of this invention is to vprovide an improved cutter chain having improved cutter bit holding means. Another object is to provide an improved cutter chain having improved cutter bit supporting means and improved means for holding 'the cutter bit in 'cutting position within the supporting means. A further object is to provide an improved cutter chain having improved holding means for a cutter b'it of the r'eversible, double-'pointed type and embodying means whereby the cutter bit may be quickly and with facility reversed with respect to the holding means. Still another object is to provide an improved detachable bit holder having associated therewith 'improved means for supporting and clamping a cutter bit Within the holder.

Other objects and advantages of the invention will, however, hereinafter more 'fully appear.

In the accompanying `drawings k'there are shown for purposes of illustration several 'forms which the invention may assume in practice.

In these drawingsc Fig. 1 is a side elevational View of one illustrative form of the 'improved cutter chain..

Fig. 2 is an end elevational view with partsV in cross section., the view taken substantially on.

line 2-12 of Fig. 1.

Fig. 3 vis a View in lonigtudinal section taken substantially on line '3 3 of Fig. 2.

Fig. 4 is a detail sectional view taken on line 4-21 of Fig. 3 with the babel-der shown in 'end elevation.

Fig. 5 is a perspective view of the cutter-bit.

supporting and clamping element..

Fig. 6 is a perspective view oi the cutter bit. Fig. '7 is -a view in longitudinal section taken in the plane of Fig. 3 showin-g a modified form Fig. 12 lis an end elevationalv view, with parts in cross section, taken substantially on line l lf2-I2 of Fig. 11.

ted at `3 to provide front and rear projections or end abutments 4 and 5, and extending inwardly from the inner surface of the slot is a socket 6. Mounted on the chain block lug is a detachable bit holder 1 having a shank 8 yfitting the socket 6 and an enlarged head 'S seated within the slot 3. The rear end surface I0 of the holder head 9 abuts the forward surface of the rear projection 5 of the block lug, and the holder is firmly held in seated position within the slot 3 by means of a transverse pin II supported at its -ends within the sides of the chain block lug and driven through an opening I2 formed in the holder shank 8. As shown in Fig. 3, extending completely through the head of the bit holder is an upwardly and forwardly inclined socket I3 for receiving a cutter bit I4, the socket shapedto lit the body of 'the cutter bit.

The cutter bit I4 is of 'substantially triangular formation in side elevation and of approximately diamond shape in cross section and has opposed cutting surfaces I5 and I6 lying in the sides of an obtuse dihedral angle and'terminating in cutting points 'Il and I8 at the same side of the bit. The cutting surfaces I5 and I? of the bit are herein of elongated diamond shape, and are individually symmetrical as to both major and minor axial lines. The apex I9 of the 'triangular portion of the bit body is adapted for reception within a correspondingly shaped socket 20 formed in a combined bit supporting and clamping element 2|. The element 2I is guided for movement within a longitudinal slot 22 formed in the bit holder head and communicating with the inclined bit receiving socket I3, and the inner end 2'3 of the supporting and clamping yelement projects within the bit receiving socket in the manner shown in Fig. 3 with an inclined surface 24 of the socket 20 engaging the inactive cutting surface I6 of the cutter bit. The socket 20 is formed with a front abutment surface 25 engaging the inner portion of the active cutting face I5 of the cutter bit. The lower straight edge of the element 2| is formed on a convex surface 26 of the lower portion of the element 2|, and the guide slot 22 is formed with a concave guiding surface with which the convex surface 26 engages. The supporting and clamping element 2| is loosely attached to the head of the bit holder by means of a transverse pin 21 fixed at its ends within the holder head and passing through a longitudinal slot 28 traversing the body of the element 2 I. Threadedly secured at 29 within the front projection 4 of the chain block lug is a set screw 30 having its rounded inner end 3I seated within a depression 32 formed in the forward face of the element 2|.

The mode of use of this form of the invention will be clearly apparent from the description given. The cutter bit holder 9 may be readily detached from the chain block lug simply by driving out the holding pin II. When the bit holder is in the position shown in Fig. 3, and the cutter bit I4 is in cutting position within the bit holder socket I3, the cutter bit may be rmly secured within the bit holder by tightening the set screw 33 -to move the supporting and clamping element2l inwardly to clamp the bit within the holder. The surface 24 of the socket 25 precludes inward movement of the cutter bit within the holder socket I3, while the surface 25 precludes outward movement of the cutter bit with respect to the holder socket. When the cutting point I1 of the cutter bit becomes dull, the cutter bit may be readily reversed end for end within the holder socket simply by loosening the set screw 3D to permit forward release of the element 2| so that the cutter bit may be readily withdrawn in an outward direction from the holder socket. When the cutter bit has been reversed end for end, it may again be clamped in position within the holder socket simply by tightening the set screw 30 to bring the supporting and clamping element 2I into its operative bit supporting and clamping position with respect to the holder. When the cutter bit is in reversed position with respect to the bit holder, the cutting surface I engages the surface 24 on the element 2l, while the then active cutting surface I6 on the bit engages the abutment surface 25 on the element 2| so that the cutting point I 8 is at that time presented to the work.

VIn the modified form of construction shown in Figs. 'I' and 8, the chain block lug 32 is transversely slotted at 33 to provide front and rear abutments 34 and 35, the front abutment 34 having a rear inclined plane surface 36. Mounted within the chain block lug is a cutter bit holder 31 having a shank 38 received in a socket 39 formed in the chain block and an enlarged head 4i! seated within the slot 33 with the rear plane surface 4I of the holder head abutting the front surface of the lug abutment 35. Extending completely through the holder head is an outwardly and forwardly inclined socket 42 for receiving the cutter bit I4. The bit holder head 40 is formed with a centrally located, longitudinal slot 43 -communicating with the bit receiving socket and opening through the forward face of the holder head, and slidingly mounted in this slot is a combined bit supporting and clamping element or wedge block 44 having an inclined front wedge surface 45 engaging the inclined rear surface 36 of the lug abutment 34. The element 44 is attached tothe holder head by means of a transverse pin 46 mounted within the sides of the holder head and passing through a slot 41 formed in the element 44. The element 44 is formed with a socket 48 for receiving the apex portion I9 of the substantially triangular-shaped bit, and this socket is formed with a surface 49 engaging the cutting surface i6 of the bit and a surface 50 engaging the inner portion of the active cutting face I5 of the bit. Threadedly secured at 5I within the forward portion of the chain block lug is a Set screw 52 engageable with the shank 38 of the bit holder for firmly securing the holder in position on the chain block. When the bit holder is inserted within the slot within the chain block lug with its shank 38 received in the chain block socket 39, the element 44 engaging the inclined surface 36 on the front lug abutment 34 causes the cutter bit to be clamped in position within the holder socket 42 by means of the element 44, the latter tightly clamping the bit in position within the holder with a wedging action. When the holder is pushed inwardly with the element 44 tightly seated against the wedge surface and the cutter bit tightly clamped in position, the set screw 52 is tightened to secure firmly the holder shank within the chain block socket. The holder may be readily released from the chain block simply by loosening the set screw, withdrawing the holder shank from the chain block socket and releasing the wedge block, it then being possible to reverse the cutter bit end for end with respect to the bit holder to present a sharp cutting point to the work. The cutter bit when in reverse position has its inactive cutting surface I5 engaging the surface 49 on the element 44, with the surface 50 engaging the then active cutting surface I6 of the bit.

In the modification shown in Figs. 9 and 10, the chain block is provided with a lateral lug 54 having a socket 55 for receiving the shank 56 of a bit holder 51. This bit holder is formed with an enlarged head 58 seated against the outer surface of the chain block lug at 59, and extending completely through the holder head is an outwardly and forwardly inclined socket 60 for receiving the cutter bit I4. Seated within the holder head and extending through the bit receiving socket is a transverse abutment pin 6I on which the inactive cutting surface of the cutter bit rests when the cutter bit is in cutting position within the holder. A clamping member 62 cooperates with the bit holder in the hol-ding of the cutter bit, and this clamping element has a shank 63 likewise projecting within the chain block socket 55 and preferably slidingly interlocked at 51 with the bit holder shank 56. This clamping member has a ledge-like surface 64 resting upon the outer surface of the chain block lug and is formed with a clamping surface 65 engaging the inner portion of the active cutting surface of the bit. Threadedly secured at 66 within the forward portion of the chain block lug is a set screw 61 for engaging the shank 63 of the clamping member to secure firmly the bit holder and clamping member in holding an-d clamping position on the chain block lug. The pin 6I prevents inward movement of the cutter bit within the holder socket, while the surface 65 on the clamping member precludes outward release of the cutter bit from the holder socket. When it is desired to release the bit holder from the chain block lug, the set screw 61 is loosened and the Shanks of the holder and clamp are withdrawn from the chain block socket. The clamping member may then be released from the holder shank by sliding the interlocking portion on the clamping member shank from the slot in the holder shank. The cutter bit may then be readily reversed end for end with respect to the holder socket to present a sharp cutting point to the work. lela-mp may thereafter The connected .to the holder yshank and the shanks .of Athe holder and .clamp then reinserted within :the blo-ck socket, the .fset :screw thereafter bein-g' tightened to iclamp firmly vthe parts fin position on the lug. .the l:cutter bit is .reversed within theholder socket, the `formerly .active :cutting `surface .I then rests against the abutment pin El., while the surface S5 'on the clamping .member engages the `then active cutting `surface IB fon the bit. i

fn the :modification shown `in Figs. 11 .and 12, the'chain'blockiis provided with fa latcralylug "B9 formed with a socket .'III. Received in the lug socket is a vcutter bit holder :"II having a shank 'I2 interlocked at 113 'with the block lug. Extending completely through the holder is an outwardly and forwardly "inclined socket 'I4 for 'receiving the cutter bit I4., .and mounted 'in the holder and extending :across the bit socket .is an abutment pin 115 on vwhich the 'inner inactive icutting surface of the bit rests. `Also 'projecting within the socket 'IIJ .is the shank VIE of Va clamping member TI. This clampingxmember is formed with a surface 'IB engaging lthe inner portion of the active cutting surface of the cutter bit. Threaded within the forward portion of the chain block lug iis a set screw 19 for engaging the shank of the clamping member :'II to .clamp tightly the cutter bit within 'the holder 'socket and to secure the holder and clamp-ing elements in holding position within the chain block lug socket. The inner inactive cutting surface I6 of the cutter bit rests against the pin while the surface I8 on Athe clamping member engages the active cutting surface lI5 of the bit, the stop pin preventing inward movement of the bit within the socket while the clamping member' precludes outward release of the cutter bit from the socket. The cutter bit holder and clamping member may be readily released frorn the lug socket simply by loosening the set screw I9 and withdrawing the clamping member from thelug socket 10. The bit holder may then be movediforwardly to vrelease .its interlocking connection with 'the lug, and the holder thereafter Withdrawn from the lug socket. When the holder Aand clamping member are released from Athe lug socket, the cutter bit I4 may be readily turned end for end with respect to the hit holder socket so that when done cutting point becomes dull, another sharp cutting point may be presented to the work. The parts may thereafter be .reinserted within the lug socket and the set screw `I9 tightened lto clamp rigidly the parts in position on the lug.

The modifications shown in Figs. '13 and 14 are somewhat similar in character. In Fig. 1,3 the chain block is formed with a lateral. lug 91 having extending completely therethrough an Aoutwardly and forwardly inclined socket `82 for receiving the Vcutter bit I4. The block lug is formed with a recess 83 communicating with the bit receiving socket 82 and having an inner inclined surface 84.. Mounted inthe recess 83 and having its inner surface engaging the inclined surface .84 .is a wedge block 85 for supporting and clamping the cutter bit I4 within the bit receiving socket. The member 85 is formed with a socket 86 for receiving the apex portion of the triangular shaped bit, and this socket is formed with a surface 81 engaging the inner inactive cutting surface of the bit and a surface Allt engaging the inner portion of the active cutting surface of the bit. The Wedge block is loosely secured within the recess 83 by means of a transverse pin89 secured within the wedge block :and having dts ends guided within 'inclined vslots i911 formed .in `the .si-'de wallsiof the recess. Secured within forward portion .of the chain :block lug is a .set screw f9iI.. When this set screw is tightened, it engages the :forward .surface of the wedge yblock 85, moving the latter rearwardly and upwardly along the inclined surface 84 to clamp `firmly thecutter bit within the bit receiving socket. The vcutter .bit may 'be readily released :from the bit receiving Asocket .simply by loosening the Yset :screw '9i to permit forward and inward 4movement .of the wedge fblock. When the Vcutter bit. is released, -it .may be readily turned end for end with yrespect to the bit .receiving socket to presenta sharp cutting vpoint to the work. When the bit tis clamped in cutting position, as yshowinin .Fi-g. i3., the .surface 81 yon Y the wedge block prevents inward movement of the cutter bit withinv the bit receiving socket, while the surface 88 on the wedge block precludes outward release of the cutter bit from the socket. In .Fig L4, the chain block is formed with a ,lateral :lug 93 having extending complete- 1y therethrough an outwardly and forwardly inclined socket 94 f-or receiving the cutter bit I4. 'I'he chain .block lug is formed with a recess 95 communicating with the bit receiving socket `94, and 'reciprocably mounted for longitudinal adiustment within this recess is a Vwedge block 96. This-wedge block has a .socket 91 for receiving the apex portion t9 of the Ysubstantially triangular shaped bit, and Vthis -socket .is formed with a surface 98 engaging the inner inactive cutting surface of the bit and a surface 99 engaging the inner portion of the active cutting face of the bit. For securing the wedge block within the recess 95, the Wedge block is formed with lateral lugs I9 guided with-in longitudinal slots IIlI formed inthe side walls of the recess. Threadedly secured within the forward portion of the chain block lug is a set screw |92. When the set screw |02 'is in its 4released position, the lugs 109 on the wedge block may be moved rearwardly into communication with vertical slots |93 so that the wedge block may be released from the recess 95, the lugs IBB moving within the slots |03 when the wedge block is moved outwardly from the recess. `When the set screw |92 is tightened, it engages the forward surface of the wedge block to move the wedge block rearwardly withinits guideway to clamp firmly the cutter bit within the bit receiving socket. The surface 98 on the wedge block supports the cutter bit against inward movement within the bit receiving socket, while the .surface 99 on the wedge block engaging the active cutting face of the bit precludes outward release of the bit with respcctV to the bit receiving socket.

.Asa result of this invention, it will be noted that an improved cutter chain is provided having improved Vmeans for supporting a cutter bit in cutting position `on a chain block and for rmly holding thev cutter Vbit in cutting position. It will further be noted that by providing an irnproved supporting structure for a cutter bit of the double-ended reversible type, the cutter bit may be readily and quickly reversed end for end, therebyto present a sharp Icutting, point to the work when the :other point 'becomes dull. Other uses and advantages of the improved cutter chain will be clearly apparent to those skilled in the art.

While there are in this application specifically described several forms which thev invention may assume'in practice, it will be understood that these forms of the same are shown for purposes of illustration, and that the invention'may be further modified and embodied in various'other forms without departing from its spirit or the scope of, the appended claims.

What I claim as new and desire to secure by Letters Patent is:

l. In a cutter chain, a chain block having a socket, a detachable holder having a shank received in said socket and an enlarged head having an inclined bit-receiving socket extending completely therethrough, means for securing said holder shank within said chain block socket, a double-ended reversible cutter bit received in said holder head socket, said holder head having a longitudinal slot entering said bit-receiving socket, and a combined supporting and clamping member supported in said longitudinal slot and projecting into said bit-receiving socket, said member engageable with said cutter bit and having a surface engaging the inner inactive cutting end of the bit for preventing inward movement'of the bit within the holder head socket and a surface engaging the active cutting end of the bit for precluding outward release of the bit from said holder head socket.

2. In a cutter chain, a chain block having a socket, a detachable bit holderhaving a shank received in said socket andan `enlarged head having an inclined bit-receiving socket extending completely therethrough, means for securing said holder shank within said chain block socket, a double-ended reversible cutter bit received in said holder head socket, said holder head having a longitudinal slot entering said bit-receiving socket, a combined supporting and clamping member supported in Said longitudinal slot and projecting into said bit-receiving socket, said member engageable with said cutter bit and having a surface engaging the inner inactive cutting end of the bit for preventing inward movement of the bit within the holder head socket and a surface engaging the active cutting end of the bit for precludingoutward release of the bit from said holder head socket, and a set screw threaded within the forward end of said chain block and engaging the forward surface of said supporting and clamping member for moving the latter rearwardly within said holder head slot, into supi porting and clamping relation with said bit.

3. In a cutter chain, achain block having a socket, a detachable bit holder having a shank received in said socket and an 'enlarged head having an inclined bit-receiving socket extending completely therethrough, means for securing said holder shank in said chain block socket, a double-ended reversible cutter bit received in said holder head socket, said holder head having a longitudinal slot entering said bit-receiving socket, and a combined supporting and clamping member supported in said longitudinal slot and,

projecting into said bit-receiving socket, said member engageable with said cutter bit and having a surface engaging the inner inactive cutting end of the bit for preventing inward movement of the bit within' the holder head socket and a surface engaging the active cutting end of the bit for precluding outward release of the bit from said holder head socket, said supporting and clamping member having a socket for receiving a portion of the bit intermediate its cutting ends, said bit-engaging surfaces forming the inner walls of said last mentioned socket.

4. In a cutter chain, a chain block having a socket, a detachable bit holder having a shank received in said socket and anr enlarged head having :an inclined bit-receiving socket extending completely therethrough, means for securing said holder shank within said chain block'socket, adouble-ended reversible cutter bit received in said vholder head socket, said bit substantially triangular in shape in side elevation, said holder head having a longitudinal slot entering said bitreceiving socket, and a combined supporting and clamping member mounted in said longitudinal slot and projecting within said holder head socket into engagement with said cutter bit, said member having a socket for receiving the portion of the cutter bit at the apex portion of the triangle, an inner surface of said last mentioned socket engaging the inner inactive cutting end of the bit for preventing inward movement of the bit within the holder head socket and another surface thereof engaging the'active cutting end of the bit for precluding outward release of the bit from said holder head socket.

5.' In a cutter chain, a chain block having. a lateral lug, said lug'being transversely slotted to provide front and rear lug abutments, said front lug abutment having a rear inclined surface land said block lug having a socket, a detachable bit holder having a shankreceived in said lug socket and an enlarged head within saidl lug slot, the r'ear surface of 'the holder head abutting the front surface of said rear lug abutment, a set screw for securing said holder shank within said lug socket, said holder head having an inclined socket extending completely therethrough for receiving a cutter bit, a double-ended reversible cutter bit received in said holder socket, anda wedge block guided on said holder and having a front inclined surface engaging the rear inclined surface on said front abutment lug, said wedge block having a surface engaging the inactive cutting end of the bit and a surface engaging the active cutting end of the bit,' said wedge block surfaces preventing displacement of the bit in either endwise direction with respect to said holder head socket, and inward movement of said holder within said block lug 4socket 'effecting movement of said wedge block along said inclined abutment lug vsurface for clamping the bit in said holder socket.

6. In a cutter chain, a chain block having a lateral lug, said lug being transversely slotted to provide front and rear lug abutments, said front lug abutment having a rear inclined surface and said block lug having a socket, a detachablebit holder having a shank received in said lug socket and an enlarged head within said lug slot, the rear surface of the holder head abutting the front surface of said rear lug abutment, a set screw for securing said holder shank within said lug socket, said holder head having an inclined socket extending completely therethrough for receiving a cutter bit, a double-ended reversible cutter bit received in said holder socket, and a wedge block guided on said holder and having a front inclined surface engaging the rear inclined surface on said front abutment lug, said wedge block having a surface engaging the inactive cutting end of the bit and a surface engaging the active cutting end of the bit, said wedge block surfaces preventing displacement of the bit in either endwise direction with respect to said holder head socket, and inward movement of said holder Within said block lug socket effecting movement of "said Wedge block `along 'said' inclined abutmentlugV surface for clamping the bit in said holder'socket,'said1wedge block `to provide front and rearlug abutments, said front lug abutment having? a rear inclined surface` and vsaid blockA lug having a socket, a

detachable bit holder having a shank received in said block socket and an enlarged headfwithin said lug slot, the rear surface of the holder head abutting the front surface ofv said rear lug.' abutment, means for securing said holder shank within said lug ysocketjsaid holder head having an inclined socket :extending completely therethrough for receiving a cutter bit, a double-ended reversible cutter bit received in said holder socket, said bit substantially triangular in shape in side elevation, and a wedge block guided on said holder and having a front surface engaging the rear inclined surface of said front abutment lug, said wedge block having a socket for receiving the portion of the bit at the apex of the triangle, an inner surface of said wedge `block socket engaging the inactive cutting end of the bit and another surface of said wedge block socket engaging the active cutting end of the bit, said wedge block surfaces preventing displacement of the bit in l'either endwise direction with respect to said holder head socket, and inward movement of said holder within the block lug socket effecting movement of said wedge block along said front lug abutment surface, for clamping said bit in said holder socket.

8. In a cutter chain, a bit support having front and rear abutment lugs, said front abutment lug having a rear inclined surface, a bit holder having a portion receivable on said support between said abutment lugs, said holder having an inclined bit-receiving socket, a cutter bit receivable in said holder socket, and a wedge block cooperating with said holder and guided thereon and engaging the cutter bit, and against which the inner end of said bit rests for securing said bit in cutting position on said bit support, said edge block having a front inclined surface engaging said rear surface on said front abutment lug, and inward movement of said holder with respect to said bit-support-abutment-lugs effecting movement of said wedge block relative to said bit support and holder for clamping said bit within said socket with the inner end of said bit resting firmly against said Wedge block.

9. In a cutter chain, a chain block having front and rear lug abutments and `a socket between said abutments, said front lug abutment having a rear inclined surface, a bit holder having a portion receivable in said chain block socket, the rear surface of the holder abutting the front surface of said rear lug abutment, said holder having an inclined bit-receiving socket for receiving a cutter bit, a cutter bit received in said holder socket, and a wedge block guided on said holder and having a front inclined surface engaging the rear inclined surface on saidfront abutment lug, said wedge block engaging said cutter bit and the inner end of the bit resting against said wedge block, and inward movement of said holder within said chain block socket effecting movement of said wedge block along said inclined abutment lug surface for clamping the bit in said holder socket with the innerlend of :said *bit resting firmly against said wedge 10. In a lcutter chain, a chain block having front and rear lug abutments'and a socket between said. abutments, said front lug abutment having a vrear inclined surface, a bit holder `having. a portionv receivable in `said chain .block socket, the rear surface ofthe holder abutting the front surface `of said rear lug abutment, "said holder having an inclined bit-receiving socket *for `receiving fa cutter bit, a double-'ended revers- Wible` cutter bit received in said holder socket, and a Wedge block 4,guided on said holder and having a front. inclined surface engaging `the rear iinclined surface on said frontvabutment lug,

said wedge block .having surfaces engaging .por- :tions uof the inactive and active `cutting ends of .the 'bit :for preventing displacement of ,the bit either forwardly or rearwardly with respect to said holder socket, inward movement of said holder within said chain block socket effecting movement of said wedge block along said inclined abutment lug surface for clamping the bit in said holder socket.

1l. In a cutter chain, a bit support having a socket and a wedging surface, a bit holder having a portion receivable in said support socket and a bit-receiving socket, a cutter bit received in said holder socket, and a Wedge block cooperating with said holder and engaging the cutter bit for holding the bit in cutting position on said bit support, said cutter bit resting at its inner end against said wedge block, said wedge block having a surface yengaging said wedging surface of said bit support, and said holder when moved inwardly into said bit support socket effecting automatic clamping of the bit within said holder socket by engagement of said wedge blocksurface with said support wedging surface with the inner end of said bit resting firmly against said wedge bl-ock, said wedge block as said bit holder is moved inwardly as aforesaid moving into bit clamping position relative to said bit support and said holder.

l2. In a cutter chain, a chain block having a socket, a detachable bit holder having integral head and shank portions, said holder received in said chain block socket and having an obliquely inclined opening extending completely through the holder head portion for receiving a cutter bit and a longitudinal slot communicating with said inclined bit-receiving opening and opening through the forward face of the holder head portion, a double-ended reversible cutter bit having cutting faces at its opposite ends terminating in cutting points, a wedge block guided in said head portion slot and projecting into said inclined bit-receiving opening, said wedge block having Surfaces engaging the adjacent portions of the active and inactive cutting faces of the bit for holding the bit against endwise movement within said inclined bit-receiving opening, means for securing said wedge block to said holder while permitting limited endwise movement of said Wedge Within said longitudinal slot relative to said holder, a set screw threaded withinthe forward end of the block and engaging the front face of said wedge block for adsocket therebetween, a detachable bit holder having integral head and shank portions, said holder received in said chain block socket with said head portion arranged between said front and rear lug portions, the rear surface of th-e head portion abutting the forward surface of said rear lug portion, said holder head portionhaving an obliquely inclined opening extending completelir therethrough for receiving a cutter bit and. a longitudinal slot communicating with said inclined bit-receiving opening and opening through the forward face of the holder head portion, a double-ended reversible cutter bit hav- Ying cutting faces at its opposite ends terminating in 'cutting points, said cutter bit received in said inclined bit-receiving opening with its active cutting point projecting outwardly and forwardly from said holder and its inner inactive cutting point projecting into said chain block socket, a

Vwedge block guided in said head portion slot and projecting into said inclined bit-receiving opening, said wedge block having surfaces engaging the adjacent portions of the active and inactive cutting faces of the bit for holding the bit against endwise movement within said inclined 'bit-receiving opening, means for securing said wedge block to said holder while permitting limited endwise movement of said wedge block within said longitudinal slot relative to said holder, a set screw threaded within the forward end of the block and engaging the front end of said wedge block for adjusting the latter rearwardly within said longitudinal slot for clamping the bit in the holder, and means for securing said holder within the chain block socket.

CHARLES F. OSGOOD. 

